We are collecting simple reaction time data of the left and right hands in response to lateralized visual auditory, and tactile signals in order to assess the pathways of sensory-motor control in males and females, left- and right-handers, and individuals using the inverted or non-inverted hand posture during writing. Serveral laboratories have found that in response to visula signals, individuals using the inverted posture do not display reaction time data consistent with the normal crossed-pathway control, as is the typical case for other people. One study has found normal crossed control in response to auditory and tactile signals in inverted writers, but it is unclear as to whether actual neural pathways were measured or whether the data reflected the effects of spatial compatibility between response hand and signal location. By using simple reaction time, instead of a go-no-go reaction time, and by having subjects respond to buttons on the opposite side of space from the response hand on half the trials, we are controlling for possible compatibility effects. Our data will allow definitive conclusions to be drawn regarding possible variations among people in their reliance on crossed or uncrossed motor pathways in response to sensory information in the visual, auditory and tactile modalities. If inverted writers display an unusual control system, this would suggest major differences between them and others in the organization of lateralized cerebral functions.